The invention resides in an infusion apparatus for administering a medicine to the body of a human or an animal, comprising at least a first element provided with a cannula for insertion into, and installation in, the body, and a second element including a hollow injection needle which is connected to a hose for the supply of the medicine, wherein the first and the second element can be releasably joined by way of a locking element so that the medicine can be supplied from the hose through the needle into the cannula.
Such injection equipment is known for example from EP-B 0 688 232. Many attemptsxe2x80x94including the arrangement disclosed in the referencexe2x80x94have been made which aimed at facilitating the handling of such equipment not only for the medical personnel such as the physicians, the nurses and other caregivers but also for the patient that is the person who handles such infusion equipment during self-treatment. Persons suffering from diabetes for example have to administer their medicines regularly by themselves either by injection of the medication by conventional injection syringes or by way of injection apparatus of the type with which the present invention is concerned.
It is pointed out that, with the type of infusion apparatus with which the present invention is concerned, basically any medicine can be introduced into the body of a human or an animal that is, the infusion apparatus is not limited to the administration of insulin.
Infusion apparatus of the type with which the present invention is concerned have been found to be particularly suitable for persons who have to be treated with a particular medicine regularly in certain time intervals since continuous new puncturing of the skin and the veins or arteries can be avoided in this way. In this way, pain and often hematoma-causing punctures of injection needles are limited to a minimum. Furthermore, people who need to use injection apparatus of the type with which the present invention is concerned are generally already quite weak as a result of the condition requiring the administration of the medicine. If then, in addition to such physical weakness, the person develops a mental repugnance and as a result, a certain insecurity, the use of infusion apparatus known in the art may result in inappropriate handling or in faulty operation. For example, in prior art infusion apparatus a connection between the first and second elements can only be established when the two elements are oriented in a predetermined way with respect to each otherxe2x80x94depending on the particular design.
Relative angular displacement of the first and second elements for example by 180xc2x0 that is, relative angular positions other than that for which the apparatus is designed will not permit a jointure of the elements. And even if the angular orientations of the two elements is correct a connection can still not be established if the two elements are slightly displaced laterally since, in addition to the locking elements, there are provided guide elements which are disposed in the same plane and which must be properly oriented so as to fit into the guide openings of the other element in order to permit joining and interlocking of the two elements.
An ill person, particularly at an advanced age, is generally not in a position to orient the two elements properly angularly and, at the same time, laterally. Furthermore, the two elements must generally be interconnected with one hand, since the cannula of the infusion apparatus is inserted for example in the vein of the other arm so that the hand of this arm is not available for the connecting procedure.
It is finally to be note that the prior art infusion apparatus as disclosed in the cited EP patent includes two tongue-like locking elements and two pin-like guide elements, and further, locking element guide structures and two openings for receiving the guide pins which all have to be fitted to one another. Their manufacture requires high precision tools which themselves are complicated and expensive. Furthermore, as a result, also the manufacture of the known infusion apparatus requires highest precision so that proper fit of the guide and locking structures is ensured. This implies of course that also the needle in the second element is properly axially oriented and inserted into the opening of the cannula in the first element when the two elements are interconnected. Consequently, not only the manufacturing tools for making the known infusion apparatus are expensive but also the process of manufacturing the infusion apparatus is expensive and difficult since a continuous precise orientation of all the parts to be engaged with one another is to be ensured.
It is therefore the object of the present invention to provide an infusion apparatus with which an inexperienced user as well is a weak user can insert, in a simple manner, the cannula into the body and can establish the connection with the infusion apparatus for the introduction of the medicine into the body by way of the two interconnected elements. It should not be necessary to accurately orient the two elements to be interconnected in an accurate rotational position with respect to each other and the two element should be easy to be inter-locked and to be disconnected. Furthermore, the needle of an element should be automatically oriented precisely with respect to the insert opening of the other element. Also, the infusion apparatus should be easy and inexpensive to manufacture so that they are affordable and can be used in large numbers.
In an infusion apparatus or supplying a medicine into the body of a patient which infusion apparatus comprises a first element including a cannula and a second element including an injection needle which is placed in sealing communication with the cannula when the first and second elements are joined, the second element includes a circular groove and the first element includes locking members which are slidably movable back and forth into and out of the groove for selectively engaging the second element to lock it when inserted into the first element.
The apparatus according to the invention has the advantage that the second element can easily be inserted into the first element without the need of maintaining proper rotational relative orientation of the two elements. Actually, the second element only needs to be inserted into a single opening in the first element in a way as it is known from coaxial plugs in the electric or electronic field. No proper rotational orientation must be observed. If the two elements are not axially properly oriented they can clearly not be joined so that a faulty interconnection is not even tried. Unlike the prior art arrangement, the apparatus according to the invention has no guide pins or locking elements, which have to be properly joined for interconnecting the two elements. No locking element needs to be actuated when the two elements are joined and interlocked. For the disconnection the locking element only needs to be disengaged using the thumb and forefinger of one hand. With the simple locking and unlocking mechanism and the precise automatic orientation of the needle relative to the opening of the cannula, the apparatus is still of simple design, whereby also the tooling expenses for the manufacture of such infusion apparatus are drastically reduced so that the apparatus can be manufactured in large number at low costs.
In order to further facilitate the insertion of the second element into the insertion opening formed in the first element, the second element is essentially circular in cross-section and the axis thereof, that is the center-point of the circle, coincides with the needle shaft.
Another feature which facilitates insertion of the second element into the insertion opening in the first element is the provision of an inclined circumferentially extending front end area of the section of the second element to be inserted into the first element. In this way, the insertion of the second element into the insertion opening of the first element is facilitated even when the two elements are not precisely aligned with respect to each other since the second element is automatically moved into proper alignment during the insertion procedure. The inclined circumferential front area of the first element furthermore opens the clamping structure upon insertion of the second element into the insertion opening of the first element. Also, the insertion opening of the first element may be inclined at its open end so that it has a funnel-like shape.
The clamping structure is preferably formed by two separate clamping arms, which are essentially parallel to each other but are resiliently movable away from, and toward, each other. When they are moved toward each other the insertion opening of the first element is unlocked so that the second element can be inserted into the insertion opening of the first element up to a predetermined end position. Upon movement of the clamping arms away from each other the second element is locked to the first element when it is in its predetermined end position.
Preferably, the locking arm include a circle segment area with a radius corresponding to the radius of annular groove formed in the second element by which the locking arms enter the groove for locking the first element to the second element. There are preferably two opposite locking arms and the circle segment spans preferably about a quarter of a circle. With the locking arms engaged in the grooves, the two elements are held firmly engaged with each other.
In order to ensure in a simple manner that the two locking arms forming the locking structure move out of the insert opening of the first element for the insertion of the second element or that they move to an unlocking position when the second element is inserted but is to be released, each locking arm includes an inclined area and the guide slot in the first element is oppositely inclined. For unlocking the two elements from each other the inclined areas of the locking arms slide along the inclined areas of the first element so that the locking arms are elastically moved apart until they are removed from the groove. The return force generated by the elastic deformation of the locking arms is sufficiently large so that the locking arms return to a locking position when the locking structure is released.
In another embodiment of the infusion apparatus, the guide structure for the locking arms extends essentially perpendicularly to the axis of the insertion opening for the second element which insertion opening is essentially circular in cross-section.
The infusion apparatus is equally suitable for use by right-handed and left-handed persons since the two locking arms forming the locking structure are essentially identical in design and are arranged symmetrically to the axis with respect to which they are movable. Also, the cannula is arranged in axial symmetry with this axis. Furthermore, movement of the locking arms for locking and unlocking of the second element occurs by movement along this axis no matter whether the two locking arms are actuated by the fingers of the right or the left hand.
In order to ensure in a simple manner that the path of movement of the locking arms with in the guide slot of the first element is limited the locking arms are preferably provided with engagement projections adapted to reach behind engagement edges, which are formed in the area of the guide structure that is the guide slot of the first element. Consequently, no other measures are needed to retain the locking arms in the guide slots once the locking arms have reached, during assembly, a position in which the engagement projections are disposed behind the engagement edges in the guide slots.
The end of the locking member may be provided with an actuating structure such as an enlarged area, which extends from the body of the first element. The actuating structure facili tates the use of the infusion apparatus for the user. It is advantageous if also the actuating structure is guided in the first element. In this way, the guided support of the whole locking member in the first element is improved.
In order to prevent a slipping of the fingers from the actuating structure the surface as area of the engagement structure, which his grasped by the user, is preferably provided with gripping means such as grooves, furrows or a rough coating.
For the same reason, it is advantageous if the side of the first element opposite the actuating structure is provided at least partially with grip-improving means so that the structure can be safely grasped with a thumb and a finger.
In another advantageous embodiment of the invention, the second element includes at its free end an essentially axial recess into which the needle projects such that its tip does not extend beyond the free end of the second element. In this way, it is ensured that, upon insertion of the second element into the insertion opening of the first element, the user will not contact the needle so that contamination of the needle is avoided and the free end of the needle is not damaged. As a result, a continuous precise axial alignment of the needle with the opening in the cannula in the first element is maintained.
In order to provide for a good mechanical stability between the two elements when they are interconnected, the infusion apparatus is so designed that the opening area of the cannula extends at least partially into the recess of the second element when the two elements are interconnected. In this way, it is ensured that any deformation of the two elements does not affect the axial alignment between the tip of the needle and the opening area of the cannula.
In order to seal the needle in the opening of the cannula when the two elements are interconnected, the inner diameter of the cannula opening in the first element may be adapted in size to the outer diameter of the needle so that the needle is tightly and sealingly received in the cannula. This however would require highest precision in the manufacture of the first and also of the second elements since such tightly fitting engagement could be achieved only if the axis of the tubular cannula would be precisely aligned with the needle. It is therefore considered to be advantage us for achieving a sealing connection between the cannula and the needle if the cannula opening is covered by a closure element which is pierced during insertion of the needle into the opening area of the cannula that is when the second element is inserted into the insertion opening of the first element, that is when the two elements are properly positioned relative to each other and interlocked.
In order to ensure that, upon disconnection of the two elements and removal of the second element from the first element from the insertion opening, the exposed opening of the cannula is not contaminated, the closure element consists preferably of an elastomer or plastomer material. Such a material can easily be pierced by the needle and, upon removal of the needle, the passage pierced into the closure element is automatically closed because of the elastic or plastic properties of the material of which the closure element consists.
The essential elements of the infusion apparatus may be made of plastic. Any plastic material may be used which is neutral that is which is compatible with human or animal tissue. Preferably, the plastic material can be injection molded so that the injection apparatus can be manufactured by injection molding machines. A suitable plastic material is for example polycarbonate.
Since the locking elements are elastically deformed in their unlocking positions, the must be made of an elastically deformable material, preferably of polyacetate, which is a strong material with good elastic deformation characteristics.
In principle the cannula can be mounted in, that is, firmly connected with, the first element during the injection molding of the first element. It has been found to be advantageous to surround the cannula at its end in the first element with a sleeve element by way of which the cannula is received in a recess formed in one end of the insertion opening for the second element. In this way, the first element can be manufactured independently of the cannula. The cannula can then be mounted together with the sleeve element into the recess of the first element for connections with the first element. This arrangement is also advantageous because it facilitates an exchange, and also cleaning, of the cannula.
In order to omit the need for further mounting means for the cannula in the first element, it is advantageous if the opening in the first element forms a suitable reception, preferably a compression mount for the sleeve element.
It is further advantageous to arrange the closure element, through which the needle extends when the second element is inserted into the first element and which forms a dust and micro-organism barrier, within the sleeve element. In this way, the closure element is replaced with each exchange of the cannula. Finally, a connecting element may be disposed in front of the sleeve element by way of which the cannula is connected to the sleeve element. The connecting element may be disposed in the sleeve element in addition to the closure element and the cannula is also supported in the sleeve element by way of a connecting element.
In order to facilitate the insertion of the cannula into the body, the second element is provided in a second embodiment of the invention with a needle of such length that its tip projects from the cannula. After the cannula has been inserted into the body with the needle disposed in the cannula, the second element with the long needle is removed and another second element with a hollow needle as first described is inserted and locked in position in the first element for the administration of a medicine.
The infusion apparatus can be sterilized in a disassembled state or in an assembled state. Sterilization can be achieved for example by ionizing irradiation, for example, by xcex2 irradiation. However, it is also possible to sterilize the apparatus by means of an oxidizing gas such as ethylene gas. In order to ensure that also the interior of the first element is contacted by the oxidizing gas when the two elements are joined, the long needle may be hollow like an infusion needle and provided with an opening leading to the area adjacent the cannula opening in the first element when the first and second elements are joined. In this way, gas can be conducted from the needle tip to the hollow space within the first element and sterilize that area and then again be discharge through the annular space between the needle and the cannula.
Below, the invention will be described in greater detail on the basis of the accompanying drawings.